Ultrasonic testing allows non-destructive verification of surfaces and interiors of various structures whose integrity may be important for operations and safety. Non-destructive testing is used throughout construction, power generation, and aeronautics industries in both manufacture/fabrication and during life of use, where various testing protocols and devices are used during maintenance, at set intervals, or following operations-impacting events. Ultrasonic testing in particular can be used by portable devices that use acoustic signals to determine a tested structure's integrity, shape, internal configuration, etc.
FIG. 1 is an illustration of data that can be returned by an ultrasonic sensor that emits a discreet acoustic signal and detects its reflection in a tested structure. For example, the ultrasonic device may be a submerged sensor emitting acoustic signals, or pings, of a detectable frequency and amplitude in water that bounce off a tested object, such as a pipe wall or boat hull, also submerged. As shown in FIG. 1, the ultrasonic device may emit a ping at t=0, detected at first peak 10. A portion of the ping may bounce off a front wall of the tested structure and be detected later at t=2 at a second peak 20 upon returning to the sensor. Another portion of the ping may pass through the front wall of the tested structure to a back wall, where it is reflected back and detected at t=6.5 at a third peak 30. By comparing the different times and amplitudes between peaks 20 and 30, a user or program may determine the thickness of the wall using the known speed of the sound through the structure and water. By emitting and sensing ultrasonic pings with such a device in FIG. 1 at several different locations, a user or program can compare variations in wall thickness and detect potential abnormalities such as voids or cracks, as well as verify structure positioning and size, like a weld or wall position and depth.
Non-destructive testing can also include visual inspection, non-visual electromagnetic inspection (like x-ray inspection), radiographic inspection with beta radiation, magnetic resonance inspection, etc. In such testing, each result typically must be paired with a relatively accurate location of the tested structure in order to verify integrity and dimensions as expected locations as well as give accurate position of detected anomalies. Where a tested structure is inaccessible or difficult to visualize by a human operator or visually-verifying program, indirect methods of verifying tested structure location can be used. For example, a testing probe may be locked on a set of tracks at known positions to verify probe position and then verify tested structure position. Or a testing probe may be positioned at verifiable locations via RFID or optical tags to derive tested structure position. Still further, visual analysis, such as KLT stabilization, can be used to identify high contrast areas, shapes, and edges in order to approximate probe position from an image.